• Structural Engineering and Mechanics
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• v.13 no.3
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• pp.313-328
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• 2002

Based on the orthotropic hypoelasticity formulation, a triaxial constitutive model of concrete is proposed. To account for increasing ductility in high confinement of concrete, the ductility enhancement is considered using so called the strain enhancement factor. It is also developed a three-dimensional finite element model for reinforced concrete structural members based on the proposed constitutive law of concrete with the smeared crack approach. The concrete confinement effects due to the beam-column joint are investigated through numerical examples for simple beam and structural beam member. Concrete at compression fibers in the vicinity of beam-column joint behaves dominant not only by the uniaxial compressive state but also by the biaxial and triaxial compressive states. For the reason of the severe confinement of concrete in the beam-column joint, the flexural critical cross-section is observed at a small distance away from the beam-column joint. These observations should be utilized for the economic design when the concrete structural members are subjected to high confinement due to the influence of beam-column joint.

• Computers and Concrete
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• v.34 no.4
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• pp.447-476
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• 2024

The current research proposes an innovative finite element model established within the context of higher-order beam theory to examine the bending and buckling behaviors of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams resting on Winkler-Pasternak elastic foundations. This two-node beam element includes four degrees of freedom per node and achieves inter-element continuity with both C¹ and C⁰ continuities for kinematic variables. The isoparametric coordinate system is implemented to generate the elementary stiffness and geometric matrices as a way to enhance the existing model formulation. The weak variational equilibrium equations are derived from the principle of virtual work. The mechanical properties of FG-CNTRC beams are considered to vary gradually and smoothly over the beam thickness. The current investigation highlights the influence of porosity dispersions through the beam cross-section, which is frequently omitted in previous studies. For this reason, this analysis offers an enhanced comprehension of the mechanical behavior of FG-CNTRC beams under various boundary conditions. Through the comparison of the current results with those published previously, the proposed finite element model demonstrates a high rate of efficiency and accuracy. The estimated results not only refine the precision in the mechanical analysis of FG-CNTRC beams but also offer a comprehensive conceptual model for analyzing the performance of porous composite structures. Moreover, the current results are crucial in various sectors that depend on structural integrity in specific environments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.545-550
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• 2014

This study provided the analytical finite element method estimating the friction-induced noise on the complex beam structure. The frictional contact model was theoretically constructed and applied to the analytical finite element squeal model. The numerical results showed that the beam structure was excited by the mode-coupling instability of the specific system modes. Also, the direction of friction was shown to influence on the dynamic instability of the modes. Besides, the unstable modal frequencies estimated from the numerical calculation were validated by the experiment of the actual beam structure.

• Journal of KSNVE
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• v.7 no.1
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• pp.61-69
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• 1997

Despite of the development in the finite element method, it is difficult to get the finite element model describing the dynamic characteristics of the complex structure exactly. Therefore a number of different methods have been developed in order to update the finite element model of a structure using vibration test data. This paper outlines the basic formulation for the frequency response function based updating method. One important advantage of this method is that the intermediate step of performing an eigensolution extraction is unnecessary. Using simulated experimental data, studies are conducted in the case of 10 DOF discrete system. The solution of noisy and incomplete experimental data is discussed. True measured frequency response function data are used for updating the finite element model of a beam and a plate. Its applicability to the joint identification is also considered.

• Steel and Composite Structures
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• v.39 no.2
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• pp.201-213
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• 2021

Currently, there is a lack of research in the design approach to avoid column wall failure in the concrete filled double skin steel tubular (CFDST) column-beam connections. In this paper, a finite element model has been developed and verified by available experimental data to analyze the failure mechanism of CFDST column-beam connections. Various finite element models with different column hollow ratios (χ) were established. The simulation result revealed that with increasing χ the failure mode gradually changed from yielding of end plate, to local failure of the column wall. Detailed parametric analyses were performed to study the failure mechanism of column wall for the CFDST column-beam connection, in which the strength of sandwiched concrete and steel tube and thickness of steel tube were incorporated. An analytical model was proposed to predict the moment resistance of the assembled connection considering the failure of column wall. The simulation results indicate that the proposed analytical model can provided a conservative prediction of the moment resistance. Finally, an upper bound value of χ was recommend to avoid column wall failure for CFDST column-beam connections.

• Steel and Composite Structures
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• v.22 no.4
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• pp.915-935
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• 2016

Steel systems composed of Reinforced Concrete column to Steel beam connection (RCS) have been raised as a structural system in the past few years. The optimized combination of steel-concrete structural elements has the advantages of both systems. Through beam and through column connections are two main categories in RCS systems. This study includes finite-element analyses of mentioned connection to investigate the seismic performance of RCS connections. The finite element model using ABAQUS software has been verified with experimental results of a through beam type connection tested in Taiwan in 2005. According to verified finite element model a parametric study has been carried out on five RCS frames with different types of lateral restraint system. The main objective of this study is to investigate the forming of plastic hinges, distribution of stresses, ductility and stiffness of these models. The results of current research showed good performance of composite systems including concrete column-steel beam in combination with steel shear wall and bracing system, are very desirable. The results show that the linear stiffness of models with X bracing and steel shear wall increase remarkably and their ultimate strength increase about three times rather than other RCS frames.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.1041-1063
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• 2014

Some results on the hydroelasticity of ultra large container ships related to the beam structural model and restoring stiffness achieved within EU FP7 Project TULCS are summarized. An advanced thin-walled girder theory based on the modified Timoshenko beam theory for flexural vibrations with analogical extension to the torsional problem, is used for formulation of the beam finite element for analysis of coupled horizontal and torsional ship hull vibrations. Special attention is paid to the contribution of transverse bulkheads to the open hull stiffness, as well as to the reduced stiffness of the relatively short engine room structure. In addition two definitions of the restoring stiffness are considered: consistent one, which includes hydrostatic and gravity properties, and unified one with geometric stiffness as structural contribution via calm water stress field. Both formulations are worked out by employing the finite element concept. Complete hydroelastic response of a ULCS is performed by coupling 1D structural model and 3D hydrodynamic model as well as for 3D structural and 3D hydrodynamic model. Also, fatigue of structural elements exposed to high stress concentration is considered.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.119-123
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• 1998

New design automation method of R/C beam based on the finite element method and the nonlinear truss model approach has been presented. The proposed method can substitute inaccurate existing method, which has limitation in its application, provide accurate and efficient design results for any type of R/C beam.

• Steel and Composite Structures
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• v.18 no.6
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• pp.1353-1368
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• 2015

A finite element model is presented for the analysis of composite steel-concrete beams based on a refined high-order theory. The employed theory satisfies all the kinematic and stress continuity conditions at the layer interfaces and considers effects of the transverse normal stress and transverse flexibility. The global displacement components, described by polynomial or combinations of polynomial and exponential expressions, are superposed on local ones chosen based on the layerwise or discrete-layer concepts. The present finite model does not need the incorporating any shear correction factor. Moreover, in the present $C^1$-continuous finite element model, the number of unknowns is independent of the number of layers. The proposed finite element model is validated by comparing the present results with those obtained from the three-dimensional (3D) finite element analysis. In addition to correctly predicting the distribution of all stress components of the composite steel-concrete beams, the proposed finite element model is computationally economic.

• Steel and Composite Structures
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• v.18 no.1
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• pp.213-233
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• 2015

A nonlinear finite element analysis (FEA) model is presented for simulating the behaviour of recycled aggregate concrete-filled steel tube (RACFST) beam-columns subjected to constant axial compressive load and cyclically increasing flexural loading. The FEA model was developed based on ABAQUS software package and a displacement-based approach was used. The proposed engineering stress versus engineering strain relationship of core concrete with the effect of recycled coarse aggregate (RCA) replacement ratio was adopted in the FEA model. The predicted results of the FEA model were compared with the experimental results of several RACFST as well as the corresponding concrete-filled steel tube (CFST) beam-columns under cyclic loading reported in the literature. The comparison results indicated that the proposed FEA model was capable of predicting the load versus deformation relationship, lateral bearing capacity and failure pattern of RACFST beam-columns with an acceptable accuracy. A parametric study was further carried out to investigate the effect of typical parameters on the mechanism of RACFST beam-columns subjected to cyclic loading.